EPC - Oilgear SERVO AMPLIFIER MODULE Part Number L723888-3xx ELECTRONIC Telephone: (414) 327-1700 Oilgear Street Issued: April 28, 2015. EPC SERVO AMPLIFIER MODULE

EPC SERVO AMPLIFIER MODULE

Part Number L723888-3xx

ELECTRONIC

Telephone: (414) 327-1700 Oilgear Fax: (414) 327-0532 2300 S. 51st Street Issued: April 28, 2015

Web Site: www.oilgear.com Milwaukee, WI USA 53219 Bulletin 836260E

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EPC 300 Series (-3xx)

User Manual

http://www.oilgear.com/



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Table of Contents

1 Introduction ............................................................................................................................................ 4

2 Basic System Overview ........................................................................................................................ 4

3 General Instructions .............................................................................................................................. 5

3.1 Password Protection........................................................................................................................5

3.2 PC Interface Groupings.................................................................................................................. 5

4 Module Configuration ........................................................................................................................... 6

4.1 General Configuration .................................................................................................................... 6

4.1.1 Password Protection (000) ....................................................................................................6

4.1.2 Operating Modes (200) .........................................................................................................6

4.1.2.1 Dynamic Function Selection with Fault Monitor ..........................................................7

4.1.2.2 Dynamic Function Selection with Watchdog Monitor ..................................................7

4.1.2.3 Static Function Selection with Watchdog Daisy Chain ................................................7

4.1.2.4 Dynamic Function Selection with Limit Monitor ..........................................................8

4.1.2.5 Static Function Selection with Fault Monitor ................................................................ 8

4.1.2.6 Static Function Selection with Watchdog Monitor ....................................................... 8

4.1.2.7 Static Function Selection with Watchdog Daisy Chain ................................................ 9

4.1.2.8 Static Function Selection with Limit Monitor .............................................................. 9

4.1.3 Program Block Configuration (21x) ....................................................................................... 10

4.1.4 EPC Hardware and Software Information ............................................................................ 11

4.1.5 USB Communication ............................................................................................................. 12

4.1.6 Update Rate ........................................................................................................................... 12

4.2 Program Configuration .................................................................................................................... 12

4.2.1 Overview ............................................................................................................................... 12

4.2.2 PI Control Algorithms ............................................................................................................ 12

4.2.3 Pressure Control Programs (40x, 41x) .................................................................................. 13

4.2.4 Flow with Pressure Limit Programs - Generation 2 (42x, 43x) ............................................. 15

4.2.5 Load Sense Control Programs (44x, 45x) .............................................................................. 18

4.2.6 Simple Flow Control Programs (46x, 47x) ............................................................................. 21

4.2.7 Pressure Control with Flow Preset Programs - Generation 2 (48x, 49x) .............................. 22

4.2.8 Advanced Control with Feed-Forward Programs - (50x, 51x) .............................................. 26

4.3 Pump Controller Configuration ....................................................................................................... 30

4.3.1 Overview ............................................................................................................................... 30

4.3.2 Configuration ........................................................................................................................ 30

4.3.2.1 Function Zero Stroke Command .................................................................................. 31

4.3.2.2 Stroke Controller .......................................................................................................... 31

4.3.2.3 HP Limiter ................................................................................................................... 32

4.3.2.4 Output Polarity ............................................................................................................. 32

4.3.2.5 Output Current Limit .................................................................................................... 33

4.3.2.6 Dither ........................................................................................................................... 33




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4.3.3 Configuration Example .......................................................................................................... 34

4.4 Analog IO Configuration ................................................................................................................. 35

4.4.1 General Purpose Analog Input Configuration ........................................................................ 35

4.4.2 LVDT Fine-Adjustable Analog Input Configuration .............................................................. 38

4.4.3 Programmable Analog Outputs ............................................................................................. 39

4.4.4 Servo Valve Driver with Stroke Feedback ............................................................................ 40

4.4.4.1 Servo Attenuation and Offset ...................................................................................... 40

4.4.4.2 Stroke Feedback Device .............................................................................................. 41

4.4.4.3 Adjustment Mode ......................................................................................................... 41

4.4.5 LVDT Adjustment Algorithm ................................................................................................ 43

4.4.5.1. Determining LVDT Configuration Range ................................................................... 43

4.4.5.2 Adjustment Algorithm .................................................................................................. 44

4.5 Advanced Configuration .................................................................................................................. 46

4.5.1 Horsepower Limit Factor Calculation .................................................................................... 46

4.5.1.1 Experimental HP Limit Factor ..................................................................................... 47

4.5.1.2 Theoretical HP Limit Factor ........................................................................................ 48

4.5.2 Ramp Configuration ............................................................................................................... 50

5 Module Diagnostics ............................................................................................................................. 5 3

5.1 Diagnostic Representation of Numbers .......................................................................................... 53

5.1.1 DAC Counts .......................................................................................................................... 53

5.1.2 Voltage and Percentages ....................................................................................................... 53

5.2 Basic Diagnostics on Front Panel ................................................................................................... 53

5.2.1 Run / Fault LED .................................................................................................................... 54

5.2.2 Valve Current LED ................................................................................................................ 54

5.2.3 Feedback LED ...................................................................................................................... 54

5.2.4 Testpoint ................................................................................................................................. 54

5.3 Basic Diagnostics with PC Interface .............................................................................................. 55

5.4 Programmable Outputs Diagnostic ................................................................................................. 56

5.5 Advanced Diagnostics ..................................................................................................................... 56

5.5.1 Module Faults ........................................................................................................................ 56

5.5.2 System Messages .................................................................................................................. 57

6 Technical Data ....................................................................................................................................... 5 8

6.1 Module Pinout ................................................................................................................................. 58

6.3 Specifications .................................................................................................................................. 59

6.4 IO Summary .................................................................................................................................... 59

6.5 Cable Recommendations and Terminal Information ....................................................................... 59

7 Technical Support ................................................................................................................................. 6 0

8 Ordering Information ........................................................................................................................... 6 1




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1 Introduction

The EPC is a fully programmable microcontroller-operated controller and

amplifier for servo controlled hydraulic pumps and valves. The unit can be

configured for several types of control applications including:

Flow Control

Pressure Control or Load Control

Flow Control with Pressure Limit (PQ-Control)

Horsepower Control (Pump Stroke and Pressure)

Pressure Control with Flow Preset

Advanced Control with Feed-Forward.

2 Basic System Overview

The EPC allows one (1) single control axis with a power amplifier to drive VS-, VV- and VM-controlled

pumps and valves. The basic pump controller configuration allows for closed loop response with both

stroke position and pressure feedback. In addition, two (2) independent function programs can be

dynamically selected with a digital input signal. The unit provides a digital output for simple diagnostics or a

watchdog signal.

Three (3) general-purpose analog inputs are provided for command and pressure feedback signals including

±10 VDC, 0-to-20 mA, or 4-to-20 mA (see Section 6.4 Note 3 for current mode resister). Additionally, one

(1) analog input is provided as a dedicated fine-adjustable LVDT stroke feedback device. The module allows

for (2) two low-power programmable output signals.

The device is configured by first assigning one of twelve (12) built-in function programs to each of the two

(2) program blocks. Typically, the output of the function programs is then passed to the Pump Controller,

which provides the valve command.

Figure 2: System Overview

Figure 1: EPC

Module

4

Analog

Outputs

AnalogInputs

Stroke Feedback Pressure Feedback

Pump

Controller

Block

Selection

Digital

Output

Diagnostics

Program Block 2

(Program 0..12)

Program Block 1

(Program 0..12)

DigitalInput




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If the full features of the module are used, up to three (3) independent closed loop PI (Proportional with

Integral) control algorithms are utilized. Most function programs provide a closed loop control algorithm for

pressure or stroke, while the Pump Controller can be configured for both stroke and power feedback.

The module is programmable through the PC Interface software. Various Forms in the software will be

discussed throughout the manual. Programming items are located in these Forms.

3 General Instructions

3.1 Password Protection

The EPC allows for edit protection of all programmable parameters. Please refer to Section 4.1.1 for a

thorough discussion of Password Protection.

3.2 PC Interface Groupings

The PC interface provides a programming and monitoring interface. A toolbar menu loosely groups

functions into Forms in the following manner:

File File, Print, and Communication Commands

General Password and Communication Setup,

Program Selection and Mode Selection

(program items 000 and 2xx)

Program Program Configuration (program items 4xx and 5xx)

Pump Controller Pump Controller Configuration

(Program items 8xx)

Diagnostics General Purpose Input Configuration,

Analog IO Configuration Fine-Adjustable Input Configuration (LVDT),

Diagnostics, Servo Driver Configuration,

Programmable Output Selections

(Program items 84x, 85x, 86x, 88x, and 93x)

Diagnostics Ramp Configuration and Advanced HP Limit Setup

Advanced Configuration (program items 87x and 810)

Language Select English, German or Italian

Help User Help

Items are programmable either through Numeric Input boxes or Drop-Down List boxes.




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4 Module Configuration

4.1 General Configuration

General Configuration parameters include Password, Mode, and Communication Setup Parameters.

4.1.1 Password Protection (000)

Program Item Range Description

000 0 to 255 Password

Table 1: Password Protection

The EPC has a simple lockout password that can be used to protect the program configuration from

accidental changes. The password is entered through program item 000 in the General Configuration

Form.

If the password is set to 249, the user will be able to modify any editable entry. Any other password

will place the device in read-only mode. The user will not be able to modify any entry in this mode.

4.1.2 Operating Modes (200)


200 0 to 7 Operating Mode:

0: Dynamic Function Selection with Fault Monitor

1: Dynamic Function Selection with Watchdog Monitor

2: Static Function Selection with Watchdog Daisy Chain

3: Dynamic Function Selection with Limit Monitor

4: Static Function Selection with Fault Monitor

5: Static Function Selection with Watchdog Monitor

6: Static Function Selection with Watchdog Daisy Chain

7: Static Function Selection with Limit Monitor

Table 2: Operating Modes

The EPC has eight (8) operating modes. For Dynamic Modes, the EPC will dynamically select

the active function program based on the state of the digital input and the Program Block

settings. For Static Modes, the EPC has only function block 1 active and the digital input may

be used for an alternative purpose defined by that particular mode described in the following

sections.

The digital output is always controlled by the mode specification.

Note: Firmware versions prior to 1.10 only support Modes 0, 1 and 2.

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4.1.2.1 Dynamic Function Selection with Fault Monitor

This operating mode is selected by setting program item 200 to 0 by choosing Mode 0:

Dynamic Function Selection with Fault Monitor from the General Configuration Form.

In this operating mode, the digital input selects which program block is active. If the digital

input is low (<5 VDC), Program Block 1 is made active and the program defined in program

item 210 is used. If the digital input is high (> 5VDC), Program Block 2 is made active and the

program defined in program item 211 is used. Refer to Section 4.1.3 for discussion of Program

Block Configuration (21x).

The digital output provides standard condition status. If no faults are present, the digital output

will be high (VSupply); If faults are present, the digital output will be low (0 VDC). Refer to

Section 5.5 for information on module fault and message conditions.

4.1.2.2 Dynamic Function Selection with Watchdog Monitor

This operating mode is selected by setting program item 200 to 1 by choosing Mode 1: Dynamic

Function Selection with Watchdog Monitor from the General Configuration Form of the PC

Interface.






The digital output provides a watchdog signal of approximately 100 Hz.

4.1.2.3 Static Function Selection with Watchdog Daisy Chain

This operating mode is selected by setting program item 200 to 2 by choosing Mode 2: Static

Function Selection with Watchdog Daisy Chain from the General Configuration Form.

In this operating mode, Program Block 1 is always active and the program defined in program

item 210 is used. Program Block 2 is always inactive and program item 211 has no function.

Refer to Section 4.1.3 for discussion of Program Block Configuration (21x).

The digital input is passed through the module into the digital output. In this way, one single

watchdog timer can be used for a number of EPC modules. One EPC module would need to be

configured for Mode 1: Dynamic Function Selection with Watchdog Monitor; the remaining

EPCs would be configured for Mode 2. Any module failure would break the daisy chain.




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4.1.2.4 Dynamic Function Selection with Limit Monitor

This operating mode is selected by setting program item 200 to 3 by choosing Mode 3:

Dynamic Function Selection with Limit Monitor from the General Configuration Form.






The digital output provides a signal as to whether the stroke command is being limited due to an

over-Power or over-Pressure condition. The over-Power condition is specified from the

Horsepower Limiter. The only supported over-Pressure condition is specified by the Flow with

Pressure Limit Control algorithm (Generation 2).

If either limiting condition is taking place, the digital output will be low (0 VDC). If no limiting

situation is taking place, the digital output will be high (Vsupply). If the Horsepower limiter is

disabled and a program other than a Flow with Pressure Limit Control program (Generation 2) is

active, the digital output will be high.

4.1.2.5 Static Function Selection with Fault Monitor

This operating mode is selected by setting program item 200 to 4 by choosing Mode 4: Static

Function Selection with Fault Monitor from the General Configuration Form of the PC

Interface.

In this operating mode, Program Block 1 is always active and the program defined in menu

210 is used. Program Block 2 is always inactive and menu item 211 has no function.

The digital output provides standard condition status. If no faults are present, the digital output

will be high (VSupply); If faults are present, the digital output will be low (0 VDC).

4.1.2.6 Static Function Selection with Watchdog Monitor

This operating mode is selected by setting menu item 200 to 5, or by choosing Mode 5: Static

Function Selection with Watchdog Monitor from the General Configuration form of the PC

Interface.



The digital output provides a watchdog signal of approximately 100 Hz.




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4.1.2.7 Static Function Selection with Watchdog Daisy Chain

This operating mode is selected by setting menu item 200 to 6 by choosing Mode 6: Static

Function Selection with Watchdog Daisy Chain from the General Configuration form of the

PC Interface.



The digital input is passed through the module into the digital output. In this way, one single

watchdog timer can be used for a number of EPC modules. One EPC module would need to be

configured for Mode 1 (Dynamic Function Selection with Watchdog Monitor) while the

remaining EPCs would be configured for Mode 2. Any module failure would break the daisy

chain.

4.1.2.8 Static Function Selection with Limit Monitor

This operating mode is selected by setting menu item 200 to 7, by choosing Mode 7: Static

Function Selection with Limit Monitor from the General Configuration form of the PC

Interface.



The digital output provides a signal as to whether the stroke command is being limited due to an

over-Power or over-Pressure condition. The over-Power condition is specified from the

Horsepower Limiter. The only supported over-Pressure condition is specified by the Flow with

Pressure Limit Control algorithm (Generation 2).

If either limiting condition is taking place, the digital output will be low (0 VDC). If no limiting

situation is taking place, the digital output will be high (VSupply). If the Horsepower limiter is

disabled and a program other than a Flow with Pressure Limit Control program (Generation 2) is

active, the digital output will be high.




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4.1.3 Program Block Configuration (21x)


210 0 to 12 Program Selection for Program Block 1

0: No Program used for Block 1

(refer to Section 4.3.2.1)

1-12: Program 1 to 12 used for Block 1

211 0 to 12 Program Selection for Program Block 2

0: No Program used for Block 2

(refer to Section 4.3.2.1)

1 to 12: Program 1 to 12 used for Block 2

Table 3: Program Block Configuration

The program block configuration parameters are used in conjunction with the module operating

modes to assign pre-defined programs to the two (2) program blocks.

Dynamic Operating Modes: These modes are referred to as “dynamic” because the digital input

selects which Program Block is active. If the digital input is low (<5 VDC), Program Block 1 is

made active and the program defined in menu 210 is used. If the digital input is high (> 5VDC),

Program Block 2 is made active and the program defined in menu 211 is used (see Example).

Static Operating Modes: These modes are referred to as “static” because Program Block 1 is

always active and menu 210 defines the active function program. Menu 211 has no function in

operating mode 2. The static operating modes also free the digital input to be used for a function

other than program selection.




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Figure 3: General Configuration Form

Example 1: Operating Mode (program item 200) is set to 0 (Dynamic Function Selection with

Fault Monitor). Program Selection for Program Block 1 (program item 210) is set to 1 (Pressure

Control) and Program Selection for Program Block 2 (program item 211) is set to 3 (Flow with

Pressure Limit Control). See Figure 3.

If the digital input is low (<5 VDC), Program Block 1 is made active and the active program is

Program 1 (Pressure Control). If the digital input is high (> 5VDC), Program Block 2 is made

active and the active program is Program 3 (Flow with Pressure Limit Control).

Example 2: Again, operating Mode is set to 0. Program Selection for Program Block 1 (program

item 210) is set to 1 (Pressure Control) and Program Selection for Program Block 2 (program

item 211) is set to 0 (No Program).

If the digital input is low (<5 VDC), Program Block 1 is made active and the active program is

Program 1 (Pressure Control). If the digital input is high (> 5VDC), Program Block 2 is made

active, but since no program is activated, the module uses a special zero function command to

command the pump controller (refer to Section 4.3.2.1 for configuration of the Function Zero

Stroke Command).

Mode 2: For operating mode 2 (Static Function Selection with Watchdog Daisy Chain) the digital

input is used as a watchdog input signal. Therefore, no dynamic function selection is possible. In

this mode, Program Block 1 is always active and program item 210 defines the active function

program. Program item 211 has no function in operating mode 2.

The program blocks are selected from the General Configuration Form.

4.1.4 EPC Hardware and Software Information

After an upload from the EPC to a PC, several non-editable parameters are shown in the General

Configuration Form. These items include the model, serial number, software version and hardware

version. See Figure 3.

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4.1.5 USB Communication

The PC software interface must be configured properly to communicate to the EPC module. The

EPC should be connected via the USB-B connecter on the front of the device, and it carries an

internal USB-232 converter, but if necessary, download the appropriate driver from

http://www.ftdichip.com/drivers/VCP.htm. The COM port number will be assigned when the

driver installs (check your device manager for that COM port #) and baud rate is listed on the

General Configuration Form. See Figure 3.

4.1.6 Update Rate

The PC interface will update on-line information as quickly as possible. Often times this can be

improved by limiting the number of Windows™ applications. Typically, the EPC update rate will be

maximized in the 2 to 3 Hz range. See Figure 3.

4.2 Program Configuration

4.2.1 Overview

The EPC offers 12 pre-defined programs. The programs range from simple flow control to

advanced functionality. Six different types of programs exist, and the module provides two distinct

copies of each program.

Programs 1 and 2 provide Pressure Control programs. Programs 3 and 4 provide Flow with

Pressure Limit Control programs. Programs 5 and 6 provide Load Sense Control programs.

Programs 7 and 8 provide Simple Flow Control programs. Programs 9 and 10 provide Pressure

Control with Flow Preset programs. Finally, Programs 11 and 12 provide Advanced Control with

Feed-Forward.

Programs 3, 4, 9, and 10 have been modified since the manual 3 revisions ago (Bulletin 83260A) to

improve performance. This software enhancement is called Generation 2. It requires EPC software

versions 1.07 or later and PC Interface software version 1.55.0014 or later. See Appendix A for

Generation 1 information.

Programs 11 and 12 require EPC software versions 1.10 or later and PC Interface software

version 1.20 or later.

Under usual circumstances, the pre-defined programs are used as outer loop control. The output of

the pre-defined programs is normally passed through to the Pump Controller module (refer to

Section 4.3.1 for an overview of the Pump Controller).

4.2.2 PI Control Algorithms

Most programs use a PI (Proportional with Integral) control scheme. Although an advanced tutorial on

digital control systems is beyond the scope of this technical document some level of knowledge and

experience is necessary to successfully implement the control programs.

The basis of a PI controller is that an output signal is produced due to a difference between a

command and feedback term (the difference is usually referred to as Error). The output signal

for a PI control is made of a proportional error signal combined with an integral error signal.


http://www.ftdichip.com/drivers/VCP.htm



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4.2.3 Pressure Control Programs (40x, 41x)


400 1 to 100 Program 1: Pressure Command Preset

401 0 to 5 Program 1: Pressure Command Source

402 1 to 5 Program 1: Pressure Feedback Source

403 0 to 1 Program 1: Program Output Destination

404 0 to 100 Program 1: KP

405 0 to 100 Program 1: KI







Table 4: Pressure Control Programs Configuration

Function Programs 1 and 2 provide for basic Pressure Control. Program 1 is configured in program

items 400 through 405 or from the Program 1 Form. Program 2 is configured in program items 410

through 415 from the Program 2 Form.

Pressure Command Preset: The Pressure Command Preset allows for direct numeric input for the

control program. The preset is configured as a percentage, with 0% being equivalent to a 0VDC input

signal and 100% being equivalent to a +10VDC signal.

Pressure Command Source: The Pressure Command Source selects the source of the pressure

command for the program. Valid entries are (0) Preset Value, (1) Analog Input 1, (2) Analog Input

2, (3) Analog Input 3, (4) LVDT 1 (Analog Input 4), or (5) Ramp 1. If the Preset Value is chosen,

the Pressure Command Preset is used as the program command.

Pressure Feedback Source: The Pressure Feedback Source selects the source of the pressure

feedback for the program. Valid entries are (1) Analog Input 1, (2) Analog Input 2, (3) Analog

Input 3, (4) LVDT 1 (Analog Input 4), or (5) Ramp 1.

Program Output Destination: The Program Output Destination selects the output of the program.

Valid entries are (0) Pump Controller or (1) Direct. If the Pump Controller is chosen, the output of the

Program will be the input to the Pump Controller module. If Direct is chosen, the output of the Program

will by-pass the Pump Controller module and is passed directly to the servo driver. Under most

circumstances, the Pump Controller should be chosen as the output destination.

KP and KI: KP and KI provide the proportional and integral constants, respectively, for the PI

control algorithm. Both terms are expressed as 0 to 100% of a maximum value. The PI control

loop can be made a P-only control loop by setting the KI term to 0. Likewise, the PI control loop

can be made an I-only control loop by setting the KP term to 0.




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Program Overview: The Pressure Control Program is a straightforward PI control

algorithm. Comparing the command to the feedback value produces an error value.

The error is multiplied by the KP and KI constants to produce the Yp and Yi

contributions to the program output.

Figure 4: Pressure Control

Program

Example: Figure 4 shows the Program 1 Form for Pressure Control. The Pressure

Command Source is Analog Input 1 (program item 401=1) and the Pressure Feedback

Source is Analog Input 2 (program item 402=2). The Pressure Command Preset has a

value of 50% (program item 400=50) although it is not used for this particular example.

The error signal is produced by comparing the command to the feedback signals:

4.91V - 4.05V = 0.86V. The Yi and Yp signals are produced from the PI controller and the

program output is roughly equal to their sum: 8.00V + 0.66V = 8.66V. The Program

Output is set to the Pump Controller (program item 403=0).




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4.2.4 Flow with Pressure Limit Programs - Generation 2 (42x, 43x)


420 0 to 100 Program 3: Flow Command Preset

421 1 to 100 Program 3: Pressure Limit Preset

422 0 to 5 Program 3: Flow Command Source

423 0 to 5 Program 3: Pressure Limit Source




427 0 to 100 Program 3: Full Scale Command

428 0 to 100 Program 3: Pressure Breakpoint Preset

429 0 to 7 Program 3: Pressure Breakpoint Source








437 0 to 100 Program 4: Full Scale Command

438 0 to 100 Program 4: Pressure Breakpoint Preset

439 0 to 7 Program 4: Pressure Breakpoint Source

Table 5: Flow with Pressure Limit Programs

Function Programs 3 and 4 provide for Flow with Pressure Limit Control. Program 3 is configured in

program items 420 through 429 in the Program 3 Form. Program 4 is configured in program items

430 through 439 in the Program 4 Form.

Flow Command Preset: The Flow Command Preset allows for direct numeric input for the control

program. The preset is configured as a percentage, with 0% being equivalent to a 0VDC input signal

and 100% being equivalent to a +10VDC signal.

Pressure Limit Preset: The Pressure Limit Preset allows for direct numeric input for the control

program. The preset is configured as a percentage, with 0% being equivalent to a 0VDC input


Flow Command Source: The Flow Command Source selects the source of the flow command for

the program. Valid entries are (0) Preset Value, (1) Analog Input 1, (2) Analog Input 2, (3) Analog

Input 3), (4) LVDT 1 (Analog Input 4), or (5) Ramp 1. If the Preset Value is chosen, the Flow

Command Preset is used as the flow command.

Pressure Limit Source: The Pressure Limit Source selects the source of the pressure limit command

for the program. Valid entries are (0) Preset Value, (1) Analog Input 1, (2) Analog Input


the Pressure Limit Preset is used as the pressure limit command.




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feedback for the program. Valid entries are (1) Analog Input 1, (2) Analog Input 2, (3) Analog Input

3, (4) LVDT 1 (Analog Input 4), or (5) Ramp 1.






KP: KP provides the proportional gain setting to control the pressure limit slope. KP is configured as

a percentage, with 0% to no proportional gain and 100% equivalent to maximum proportional gain.

Pressure Breakpoint Preset: The Pressure Breakpoint Preset allows for direct numeric input. The

preset has a slightly different characteristics depending on the value of its entry.

If the Pressure Breakpoint Source is set to 0 (Preset Value), the preset is configured as a

percentage, with 0% equivalent to a 0VDC input signal and 100% equivalent to a +10VDC signal.

This value is used as the Pressure Breakpoint command.

If the Pressure Breakpoint Source is set to 6 (Limit Offset), the preset is configured as a

percentage, with 0% equivalent to a 0VDC input signal and 100% equivalent to a -10VDC offset

signal. The offset value is added to the Pressure Limit Source signal to make the Pressure

Breakpoint command.

Finally, if the Pressure Breakpoint Source is set to 7 (Limit Attenuation), the preset is configured as

a percentage of the Pressure Limit Source, with 0% equivalent to a 0VDC input signal and 100%

equivalent to the Pressure Limit Source. This value is used as the Pressure Breakpoint command.

Pressure Breakpoint Source: The Pressure Breakpoint Source selects the source of Pressure

Breakpoint command. Valid entries are (1) Analog Input 1, (2) Analog Input 2, (3) Analog Input 3,

(4) LVDT 1 (Analog Input 4), (5) Ramp 1, (6) Limit Offset, (7) Limit Attenuation, (8) Reference

Offset or (9) Reference Attenuation.

Program Overview: The Flow with Pressure Limit Control Program is a sloping pressure limiting

control program similar to the control schemes used in Oilgear Analog Rack systems.

The algorithm will begin to limit the Flow command once the Pressure Feedback value is greater than

the Pressure Breakpoint command. Comparing the Breakpoint command to the Feedback value

produces an error value. The error is multiplied by the KP constant to produce the Yp limit signal,

which is summed with the full-scale command. The summation of the full-scale command and the

YP limit signal in turn sets a limit to the Flow command. If the Breakpoint Pressure Limit command

is greater than the Feedback signal, the Flow command will only be limited by the full- scale

command.

If using EPC software version 1.06 or earlier, see Appendix A for Generation 1 control.




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Figure 5: Flow with Pressure Limit Program

Example: Figure 5 shows Program 3 Form for Flow with Pressure Limit. The Flow Command

Source is Analog Input 1 (program item 422=1). The Flow Command Preset is set to 10%

(program item 420=10) although the Flow Command Preset is not used in this example.

The Pressure Limit Source command is the Preset Value (program item 423=0), therefore the

pressure limit command is set at a 70% level (program item 421=70). The Pressure Feedback

Source is Analog Input 2 (program item 424=2).

The Pressure Breakpoint Source is Limit Offset (program item 429=6). The Pressure Breakpoint

Preset is set to 10% (program item 428=10). The Pressure Breakpoint value is the Pressure Limit

minus the Pressure Breakpoint Preset: 7.00V-1.00V = 6.00V. Note there is a slight conversion error

in this example. The Pressure Limit Preset is 70 but at the Pressure Limit Source it is 6.99V instead

of 7.00V.

The error signal is produced by comparing the Pressure Breakpoint Source to the Feedback signal:

6.00V - 6.95V = -0.95V. The error is multiplied by the KP constant to produce the Yp limit

-0.95V x 10.26 = -9.75V. A KP value of 64 equals a 10.26 KP constant.

The Pressure Limit command is summed with the Full-Scale command to set the limit for the Flow

command: 10.0V - 9.75V = 0.25V. Finally, the Program Output is set to the Pump Controller

(program item 425=0).




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4.2.5 Load Sense Control Programs (44x, 45x)


440 1 to 100 Program 5: Pressure Point 2 Preset

441 1 to 100 Program 5: Delta Pressure Preset


443 0 to 5 Program 5: Pressure Point 2 Source

444 0 to 5 Program 5: Delta Pressure Source






450 1 to 100 Program 6: Pressure Point 2 Preset

451 1 to 100 Program 6: Delta Pressure Preset



454 0 to 5 Program 6: Delta Pressure Source






Table 6: Load Sense Programs Configuration

Function Programs 5 and 6 provide for Load Sense Control. Program 5 is configured in program

items 440 through 449 from the Program 5 Form. Program 6 is configured in program items 450


Pressure Point 2 Preset: The Pressure Point 2 Preset allows for direct numeric input for the

control program. The preset is configured as a percentage, with 0% being equivalent to a 0VDC

input signal and 100% being equivalent to a +10VDC signal.

Delta Pressure Preset: The Delta Pressure Preset allows for direct numeric input for the control



Pressure Limit Preset: The Pressure Limit Preset allows for direct numeric input for the control






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Pressure Point 2 Source: The Pressure Point 2 Source selects the source of the pressure point

2 signal for the program. Valid entries are (0) Preset Value, (1) Analog Input 1, (2) Analog Input


the Pressure Point 2 Preset is used as the delta pressure point 2 command.

Delta Pressure Source: The Delta Pressure Source selects the source of the delta pressure signal

for the program. Valid entries are (0) Preset Value, (1) Analog Input 1, (2) Analog Input 2, (3)

Analog Input 3), (4) LVDT 1 (Analog Input 4), or (5) Ramp 1. If the Preset Value is chosen, the

Delta Pressure Preset is used as the delta pressure command.

Pressure Limit Source: The Pressure Limit Source selects the source of the pressure limit



the Pressure Limit Preset is used as the pressure limit command.

Pressure Point 1 Source: The Pressure Point 1 Source selects the source of the pressure feedback

for the program. Valid entries are (1) Analog Input 1, (2) Analog Input 2, (3) Analog Input 3, (4)

LVDT 1 (Analog Input 4), or (5) Ramp 1.










Orifice

Figure 6: Load Sense Circuit

ΔP = P1 - P2

EPC

Pressure P1

Pressure P2

P P

U U




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Program Overview: The Load Sense Control Program is one of the more complex control

algorithms supplied with the EPC. The goal of the load sense control is to maintain a pressure

difference across an orifice (refer to Figure 6). Typically, two pressure transducers would be used to

monitor two points in the hydraulic circuit. The pump flow would be controlled such that P = P1 -

P2.

In addition to this basic control, a pressure limiter is added to ensure that the down-flow pressure at P2

does not reach a critical point. The controller command is the sum of the Point 2 Pressure and Delta

Pressure signals, limited by the Pressure Limit Command. Comparing this command with the Point 1

Pressure signal results in an error value. The error is multiplied by the KP and KI constants to

produce the Yp and Yi contributions to the program output signal.

Figure 7: Load Sense Program

Example: Figure 7 shows Program 5 Form for Load Sense. The Delta Pressure Source is set to the

Delta Pressure Preset Value of 10% (program item 444=0 and program item 441=10). The Pressure

Point 2 Source is Analog Input 1 (program item 443=1), therefore the command is 1.00V

+1.54V = 2.54V.

The Pressure Limit Source is set to the Pressure Limit Preset Value of 50% (program item 445=0

and program item 442=50). In this case, the previous command value is not limited, since the

command (2.54V) is less than the Pressure Limit Command (5.00V).

The error signal is produced by comparing the Command to the Pressure Point 1 signals: 2.54V -

2.24V = 0.30V. The Yi and Yp signals are produced from the PI controller and the Program Output is

roughly equal to their sum: 5.00V + 0.24V = 5.24V. The Program Output is set to the Pump

Controller (program item 447=0).




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4.2.6 Simple Flow Control Programs (46x, 47x)








Table 7: Simple Flow Programs Configuration

Function Programs 7 and 8 provide for Simple Flow Control. Program 7 is configured in program

items 460 through 464 from the Program 7 Form. Program 8 is configured in program items 470







Input 3, (4) LVDT 1 (Analog Input 4), or (5) Ramp 1. If the Preset Value is chosen, the Flow

Command Preset is used as the flow command.


Valid entries are (0) Pump Controller or (1) Direct. If the Pump Controller is chosen, the output of

the Program will be the input to the Pump Controller module. If Direct is chosen, the output of the

Program will by-pass the Pump Controller module and passed directly to the servo driver. Under

most circumstances, the Pump Controller should be chosen as the output destination.

Program Overview: The Simple Flow Control Program is by far the least complex control

algorithm. In fact in does little more than transfer an analog or fixed input directly to the Pump

Controller.

Figure 8: Simple Flow Program

Example: Figure 8 shows the Program 7 Form for Flow Control. The Flow Command Source is

Analog Input 1 (program item 461=1). The Flow Command Preset is set to 10% (program item

460=10) although the preset is not used in this example. The Program Output is set to the Pump

Controller (program item 464=0).




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4.2.7 Pressure Control with Flow Preset Programs - Generation 2 (48x, 49x)










488 0 to 100 Program 9: Q to P Control Switch Preset

489 0 to 7 Program 9: Q to P Control Switch Source









498 0 to 100 Program 10: Q to P Control Switch Preset

499 0 to 7 Program 10: Q to P Control Switch Source

Table 8: Pressure Control with Flow Preset Programs

Function Programs 9 and 10 provide for Pressure Control with Flow Preset. Program 9 is configured

in program items 480 through 489 in the Program 9 Form. Program 10 is configured in program

items 490 through 499 in the Program 10 Form.




Pressure Command Preset: The Pressure Command Preset allows for direct numeric input for the

control program. The preset is configured as a percentage, with 0% being equivalent to a 0VDC input




Input 3), (4) LVDT 1 (Analog Input 4), or (5) Ramp 1. If the Preset Value is chosen, the Flow

Command Preset is used as the Flow command.

Pressure Command Source: The Pressure Command Source selects the source of the pressure



the Pressure Command Preset is used as the Pressure command.




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feedback for the program. Valid entries are (1) Analog Input 1, (2) Analog Input 2, (3) Analog

Input 3, (4) LVDT 1 (Analog Input 4), or (5) Ramp 1.






KP: KP provides the proportional gain setting to control the pressure limit slope. KP is configured as

a percentage, with 0% to no integral gain and 100% equivalent to maximum proportional gain.

KI: KI provides the integral gain setting to PI control loop of the program. KI is configured as a

percentage, with 0% to no proportional gain and 100% equivalent to maximum integral gain.

Q to P Control Switch Preset: The Q to P Control Switch Preset allows for direct numeric input. The

preset has a slightly different characteristics depending on the value of Q to P Control Switch Source

entry.

If the Q to P Control Switch Source is set to 0 (Preset Value), the preset is configured as a

percentage, with 0% equivalent to a 0VDC input signal and 100% equivalent to a +10VDC signal.

This value is used as the toggle point between Pressure and Flow control.

If the Q to P Control Switch Source is set to 6 (Limit Offset), the Preset is configured as a

percentage, with 0% equivalent to a 0VDC input signal and 100% equivalent to a -10VDC offset

signal. The offset value is added to the Pressure Command Source signal to make the Toggle Point

between Pressure and Flow control.

Finally, if the Q to P Control Switch Source is set to 7 (Limit Attenuation), the Preset is

configured as a percentage, and the Control Switch Toggle Point will be equal to the percentage of

the Pressure Command signal.

Q to P Control Switch Source: The Q to P Control Switch Source selects the source of the Flow

to Pressure Toggle Point command. Valid entries are (1) Analog Input 1, (2) Analog Input 2, (3)

Analog Input 3, (4) LVDT 1 (Analog Input 4), (5) Ramp 1, (6) Limit Offset or (7) Limit Attenuation.

Program Overview: The Pressure with Flow Preset Control Program functions as either Flow

Control or Pressure Control, depending on whether the feedback pressure is greater or less than the Q

to P Control Switch signal.

Under most circumstances, the control begins as a Flow Control. The algorithm will switch from a

Flow Control to Pressure Control once the feedback pressure signal is greater than the Q to P Control

Switch command. Once in Pressure Control, the Pressure command is compared to the feedback

value to produce an error value. The error is multiplied by the KP and KI constants to produce the

Yp and Yi contributions of the program output. In the pressure mode, the Flow command acts as a

limit to the pressure control loop.

If using EPC software version 1.06 or earlier, see Appendix A for Generation 1 control.




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Figure 9: Pressure Control with Flow Preset Program in Pressure Mode

Example: Figure 9 shows Program 9 Form for Pressure Control with Flow Preset in Pressure

Mode. The Flow Command Source is Analog Input 1 (program item 482=1). The Flow Command

Preset is set to 10% (program item 480=10) although the Flow Command Preset is not used in this

example.

The Pressure Command Source command is the Preset Value (program item 483=0), therefore

the pressure limit command is set at a 50% level (program item 481=50). The Pressure Feedback

Source is Analog Input 2 (program item 484=2).

The Q to P Control Switch Source is Limit Offset (program item 489=6). The Q to P Control

Switch Preset is set to 10% (program item 488=10), therefore the Q to P Toggle Point is 5.00V -

1.00V = 4.00V.

The error signal is produced by comparing the Pressure Command Source to the Feedback signal:


Pressure command is roughly equal to their sum: 2.50V + 2.36V = 4.86V.

Since the Pressure Feedback (4.40V) is greater than the Q to P Control Switch (4.00V), the

program is in Pressure Control. The Pressure command is limited by the Flow command. Since

the Pressure command (4.86V) is less than the Flow command (9.00V), it is not limited. Finally,

the Program Output is set to the Pump Controller (program item 425=0).




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Figure 10: Pressure Control with Flow Preset Program in Flow Mode

Example: Figure 10 shows Program 9 Form for Pressure Control with Flow Preset in the Flow

Mode. The Flow Command Source is Analog Input 1 (program item 482=1). The Flow Command

Preset is set to 10% (program item 480=10) although the Flow Command Preset is not used in this

example.

The Q to P Control Switch Source is Limit Offset (program item 489=6). The Q to P Control

Switch Preset is set to 10% (program item 488=10), therefore the Q to P Toggle Point is 5.00V -

1.00V = 4.00V.

The error signal is produced by comparing the Pressure Command Source to the Feedback signal:


Pressure Command is roughly equal to their sum: 0.00V + 6.33V = 6.33V.

Since the Pressure Feedback (3.40V) is less than the Q to P Control Switch (4.00V), the program is in

Flow Control. The Flow Command (9.00V) is simply passed through to the Program Output. Finally,

the Program Output is set to the Pump Controller (program item 425=0).




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4.2.8 Advanced Control with Feed-Forward Programs - (50x, 51x)


500 1 to 100 Program 11: Command Preset

501 0 to 5 Program 11: Command Source

502 1 to 5 Program 11: Feedback Source


504 -10 to 10 Program 11: Command Offset

505 0.06 to 2 Program 11: Command Gain



510 1 to 100 Program 12: Command Preset

511 0 to 5 Program 12: Command Source

512 1 to 5 Program 12: Feedback Source


514 -10 to 10 Program 12: Command Offset

515 0.06 to 2 Program 12: Command Gain



Table 9: Advanced Control with Feed-Forward Programs

Function Programs 11 and 12 provide for Advanced Control with Feed-Forward. Program 11 is

configured in program items 500 through 507 in the Program 11 Form. Program 12 is configured in

program items 510 through 517 in the Program 12 Form.

Command Preset: The Command Preset allows for direct numeric input for the control program.

The preset is configured as a percentage, with 0% being equivalent to a 0VDC input signal and

100% being equivalent to a +10VDC signal.

Command Source: The Command Source selects the source of the command for the program.

Valid entries are (0) Preset Value, (1) Analog Input 1, (2) Analog Input 2, (3) Analog Input 3), (4)

LVDT 1 (Analog Input 4), or (5) Ramp 1. If the Preset Value is chosen, the Command Preset is

used as the Command.

Feedback Source: The Feedback Source selects the source of feedback for the program. Valid

entries are (1) Analog Input 1, (2) Analog Input 2, (3) Analog Input 3, (4) LVDT 1 (Analog Input

4), or (5) Ramp 1.

Program Output Destination: The Program Output Destination selects the output of the

program. Valid entries are (0) Pump Controller or (1) Direct. If the Pump Controller is chosen,

the output of the Program will be the input to the Pump Controller module. If Direct is chosen, the

output of the Program will by-pass the Pump Controller module and is passed directly to the servo

driver. Under most circumstances, the Pump Controller should be chosen as the output

destination.




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Command Offset: The Command Offset is used to apply a voltage offset to the Command Signal

of the program. The voltage offset can be in the range of -10VDC to +10VDC in 0.1VDC

increments, although the resulting signal cannot extend beyond the maximum input range of

-10VDC to +10VDC. The resulting signal multiplied the Command Gain, determines the Open

Loop or Feed-Forward signal for the program.

Command Gain: The Command Gain is used to apply a voltage gain to the Command Signal after

the Command Offset Voltage is applied. The voltage gain can be in the range of 0.0625 attenuation

to x2 gain in 0.0625 increments, although the resulting signal cannot extend beyond the maximum

input range of -10VDC to +10VDC. The resulting signal determines the Open Loop or Feed-

Forward signal for the program.

KP: KP provides the proportional gain setting to PI control loop of the program. KP is configured as

a percentage, with 0% to no proportional gain and 100% equivalent to maximum proportional gain.

KI: KI provides the integral gain setting to PI control loop of the program. KI is configured as a

percentage, with 0% to no integral gain and 100% equivalent to maximum integral gain.

Open Loop: The program is in Open Loop only when the Mode Selection (200) is in the Static

Mode and the digital input is low.

Closed Loop: The program is in Closed Loop when the Mode Selection (200) is in the Static

Mode with the digital input high or in the Dynamic Mode.

Program Overview: The Advanced Control with Feed-Forward Program in Closed Loop is a PI

control with an adjustable Feed-Forward signal. Comparing the command to the feedback values

produces an error value. The error is multiplied by the KP and KI constants to produce the YP and

YI contributions of the PI controller. This signal is then summed with the feed-forward signal to

produce the output signal.

The Advanced Control with Feed-Forward Program in Open Loop simply modifies a command

with an offset and gain producing a output signal. The PI control is not used.

If using EPC software version prior to 1.10, this program is not available.




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Figure 11: Advanced Control with Feed-Forward Program in Closed Loop

Example: Figure 11 shows Program 11 Form for Advanced Control with Feed-Forward in Closed

Loop. The Command Source is Analog Input 1 (program item 501=1). The Command Preset is set

to 10% (program item 500=10) although the Command Preset is not used in this example.

The Feedback Source is Analog Input 2 (program item 502=2).

The error signal is produced by comparing the Command Source to the Feedback signal: 1.00V -

1.30V = -0.30V. The Yi and Yp signals are produced from the PI controller and the PI controller

output command is roughly equal to their sum: -2.50V + (-3.87V) = -6.37V.

The Command is offset and multiplied by the gain: (1.00V + 0.5V) x 1.5 = 2.25V. This Feed-

Forward Command is then summed with PI control output: 2.25V + (-6.37V) = -4.12V. Finally, the

Program Output is set to the Pump Controller (program item 503=0).




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Figure 12: Advanced Control with Feed-Forward Program in Open Loop

Example: Figure 12 shows Program 11 Form for Advanced Control with Feed-Forward in Open

Loop. The Command is offset and multiplied by the gain: (1.00V + 0.5V) x 1.5 = 2.25V. This

Feed-Forward Command is then summed with the Open Loop output: 2.25V +0.0V = 2.25V.

Finally, the Program Output is set to the Pump Controller (program item 503=0).




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4.3 Pump Controller Configuration

4.3.1 Overview

The Pump Controller provides the basic functionality of the module: to provide closed loop stroke

feedback control for the servo valve. In addition to stroke feedback, the Pump Controller module can

be configured for horsepower limitation.

Under usual circumstances, the pre-defined programs are used as outer loop control while the Pump

Controller provides inner loop control. The output of the pre-defined programs is very nearly always

passed through to the Pump Controller module (refer to Section 4.2.1 for an overview of the pre-

defined Program modules).

4.3.2 Configuration


800 0 to 5 Pump Controller and HP Limiter:

Stroke Feedback Source

801 0 to 100 Pump Controller:

Function Zero Stroke Command

802 0 to 1 Pump Controller: Output Polarity

803 15 to 100 Pump Controller: Output Current Limit

804 0 to 100 Pump Controller: KP

805 0 to 100 Pump Controller: KI

810 0 to 100 HP Limiter: Reference

811 0 to 5 HP Limiter: Pressure Feedback Source

812 HP Limiter: Spare

813 0 to 100 HP Limiter: KP

814 0 to 100 HP Limiter:

875 0 to 255 Dither

Table 10: Pump Controller Configuration




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4.3.2.1 Function Zero Stroke Command

Normally, the Active Program Block provides the command to the Pump Controller. For certain

applications, it might be desirable to have the ability to switch between two function programs,

and the EPC provides that feature by allowing two program blocks selectable by the digital input.

In some circumstances, a second program is not needed but some type of state is desired. A

prime example would be a stand-by mode in which a fixed stroke would be commanded. In this

circumstance, the user could place a pre-defined program in block 1 and select program 0 for

block 2 (please refer to Section 4.1.3 regarding Program Block Configuration (21x).

The Function Zero Stroke Command is configured by program item 801 or from the Pump

Controller Form. It is expressed as a value from 0 to 100%, where 0 equals full negative current,

100 equals full positive current, and 50 represents neutral or no current. A Function Zero Stroke

Command of 75, for instance, would provide a 50% stroke command to the valve.

4.3.2.2 Stroke Controller

The Stroke Controller portion of the Pump Controller is configured by selecting a Stroke

Feedback Source (program item 800) and setting values for KP (program item 804) and KI

(program item 805) for the Stroke PI Controller. These values can be optimal adjusted from

the Pump Controller Form.

Stroke Feedback Device: The Stroke Feedback Device determines which signal the command to

the Stroke Controller is compared to. Valid entries are (0) Open Loop, (1) Analog Input 1, (2)

Analog Input 2, (3) Analog Input 3, (4) LVDT 1 (Analog Input 4), or (5) Ramp 1. If Open Loop

is chosen, the stroke controller is disabled and the command is passed directly through to the

output.





The command to the stroke controller is from either the Active Program or the Function Zero

Stroke Command (or by the HP-limited adjustment of this command, please refer to Section

4.3.2.3). An error signal is produced by comparison of this command to the stroke feedback

signal. The PI loop produces Yp and Yi, determined by the error signal and the KP and KI

constants, respectively. The stroke controller output is made by the summation of Yp and Yi.

The Stroke Controller is disabled if the Stroke Feedback Source (program item 800) is selected as

Open Loop.

The Pump controller relies on the stroke feedback device being configured correctly. Please

refer to Section 4.4.5 regarding the LVDT Adjustment Algorithm.




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4.3.2.3 HP Limiter

The HP Limiter can be configured to limit the command to the stroke controller (refer to Section

4.3.2.2). This portion of the Pump Controller is configured by selecting a Stroke Feedback Source

(program item 800), Pressure Feedback Device (program item 811) and setting values for KP

(program item 813) and KI (program item 814) for the HP Limiter PI Controller. Additionally, a

HP Limit Factor (program item 810) must be entered (please refer to Section 4.6.2 regarding the

HP Limit Factor Calculation). These values can be optimal adjusted from the Pump Controller

Form.

Stroke Feedback Source: The Stroke Feedback Source determines which stroke signal is used in

the HP calculation (this is the same stroke feedback used in the Stroke Controller, refer to Section

4.3.2.2). Valid entries are (0) Open Loop, (1) Analog Input 1, (2) Analog Input 2, (3) Analog

Input 3, (4) LVDT 1 (Analog Input 4), or (5) Ramp 1. If Open Loop is chosen, the stroke

controller is inactive, but the HP Limiter can be active, as long as a Pressure Feedback Source is

configured. In this case, the module uses the pump controller command as the stroke feedback.

Pressure Feedback Source: The Pressure Feedback Source determines which pressure signal

is used in the HP calculation. Valid entries are (0) No HP Limit, (1) Analog Input 1, (2) Analog

Input 2, (3) Analog Input 3, (4) LVDT 1 (Analog Input 4), or (5) Ramp 1. If No HP Limit is

chosen, the HP Limiter is inactive and the pump controller command will be passed directly to the

stroke controller.





The product of Pressure and Stroke signals is compared to the HP Limit Factor (program item

810). If the product is greater than the factor, the feedback HP is greater than the allowed HP,

and the pump controller command is adjusted through the Yp and Yi contributions of the HP

Limiter PI controller. The HP Limiter works only as a limiter; the pump controller command is

not manipulated if the HP Limit Factor is greater than the calculated HP.

The HP Limiter relies on the HP Limit Factor being configured correctly. Please refer to

Section 4.5.1 regarding the HP Limit Factor Calculation.

4.3.2.4 Output Polarity

Module Polarity is selected from program item 802 from the Pump Controller Form. Polarity

(program item 802) is either (0) Normal or (1) Inverted.




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4.3.2.5 Output Current Limit

The Module can be current limited to protect the valve or limit stroke. The current limit is

selected from program item 803 of the Pump Controller Form and is expressed as 0 to 100% of

the maximum current of the module (250mA).

Current is limited in each direction, so a Current Limit of 50% will limit the current to -50% to

+50% of the maximum.

4.3.2.6 Dither

The EPC provides for a dither signal that is superimposed on the final output to the current

driver. The dither is set from the Pump Controller Form (the dither option is only available for

EPC modules with software version of 1.05 or later).

The dither frequency is fixed at 200Hz. The amplitude of the dither signal is expressed in DAC

counts, with 0 equal to no dither and 255 equal to maximum dither (approximately 12.5% of

maximum controller current).

Table 11 below shows several examples of dither values in DAC counts converted into

percent (%) and current (mA) for EPC3. The maximum current for EPC3 is 250mA.

Dither (DAC count) Dither (%) Dither (mA)

0 0.0% 0.00mA

51 2.5% 6.26mA

102 5.0% 12.52mA

154 7.5% 18.75mA

208 10.0% 25.00mA

255 12.5% 31.25mA

Table 11: Dither Examples




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4.3.3 Configuration Example

Figure 13: Pump Controller Configuration

Figure 13 shows the Pump Controller Module Form. The Diagnostic screen shows that Program

3 is active and passes the command of 7.11V to the Pump Controller. The Function Zero Stroke is

set to 50% (program item 801=50), so if no program was active a neutral stroke would be the

Pump Controller command signal.

The Pressure Feedback Source is Analog Input 1 (program item 811=1) and the Stroke Feedback

Source is LVDT (program item 800=4). The internal HP calculation based on these pressure and

stroke signals results in a value of 4.56V. The HP Limit Factor of 28% results in a value of 2.80V, so

the actual HP is greater than the allowed HP. The error signal is the difference of these calculated

numbers is 2.80V - 4.56V = -1.76V. The HP Limit is made up of the Yi and Yp contributions

computed from the HP Limiter PI controller.

The resulting Command with HP Limit is 7.11V - 0.69V = 6.42V. This command, along with the

Stroke Feedback signal is passed to the Stroke Controller, where the error signal is 6.42V - 8.31V =

- 1.89V . This error signal is used for the Stroke Controller PI calculations, and the output is equal to

the Yi and Yp contributions is 0.00V - 5.90V = -5.90V.

Module Polarity is set to Invert the module output (program item 802=1) so the -5.90V signal

becomes 5.90V. Finally, the current is limited to 50% of maximum, so the 5.90V signal decreases to

5.00V.




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4.4 Analog IO Configuration

The EPC module provides four Analog Inputs, two Analog Outputs and a Current Driver: Analog Inputs

1, 2 and 3 are referred to as General Purpose Analog Inputs and have a maximum input range of -

10VDC to +10VDC. Analog Input 4 is usually referred to as LVDT Input. This input is intended for

sinusoidal LVDT input. Analog Outputs 1 and 2 are programmable with a range of -10VDC to

+10VDC. The Current Driver is either a Linear or PWM signal to drive a valve.

.

4.4.1 General Purpose Analog Input Configuration


850 -10V to 10V Analog Input 1: Offset

851 0.125 to 4 Analog Input 1: Gain

852 0 to 1 Analog Input 1: Polarity

853 0 to 1 Analog Input 1: Current Fault Enable









Table 12: General Purpose Analog Input Configuration

Program items 850 through 853 are used to configure Analog Input 1, program items 860 through

863 are used to configure Analog Input 2 and program items 880 through 883 are used to configure

Analog Input 3. The Analog Inputs are configured from the Analog Input Configuration Form (select

menu Diagnostics and then Analog IO Configuration).

Offset: A voltage offset can be applied to the Analog Input. The voltage offset can be in the range of

-10VDC to +10VDC at 0.1VDC increments. The Analog IO Configuration Form allows for the

direct entry of a voltage offset.




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Gain: A limited gain factor can be applied to the Analog Inputs. Values in the range of a 0.125

attenuation to a 4 gain at 0.125 increments are available. The Analog IO Configuration Form

allows for the direct entry of a gain. Table 13 lists the 32 gains available.

Gain Gain Gain Gain

0.125 1.125 2.125 3.125

0.250 1.250 2.250 3.250

0.375 1.375 2.375 3.375

0.500 1.500 2.500 3.500

0.625 1.625 2.625 3.625

0.750 1.750 2.750 3.750

0.875 1.875 2.875 3.875

1.000 2.000 3.000 4.000

Table 13: Analog Input Gain Settings

The resulting voltage is limited to the -10VDC to +10VDC range.

Polarity: The Polarity setting is set to either (0) Normal or (1) Inverted. Inverting the input in this

way would be equivalent to reversing wire leads to the module. In fact, a better long term solution to

using the invert setting would be to reverse the wire leads to the module.

Current Fault Enable: The Current Fault is set to either Disabled or Enabled and is designed for use

when a 4-to-20mA input device is used. The EPC module requires a 500 resistor across (in

parallel) the Analog Input terminal pins (see Figure 20). If used, a 4-to-20mA input device will

result in a voltage from +2VDC (4mA) to +10VDC (20mA) to the module. If the Current Fault is

enabled, the module will set a System Message if this voltage falls below +1.5VDC

(approximately 3mA).

The four configuration settings are used together to configure the general purpose analog inputs.

The order of monitoring/configuration is:

(1) A Fault is reported if the Current Mode Fault is enabled and the current supplied to the

module falls below 3mA.

(2) Offset Voltage by Offset Setting.

(3) Multiply Voltage by Gain Setting.

(4) Invert Analog Input (if Polarity Invert set).




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Example 1: A user wants a 4-20mA signal at Analog Input 1 to control a bi-directional pump

(command range of +/- 10VDC).

First the user would enable the current fault for Analog Input 1 (program item 853=1) and place a

500 ohm resistor across the analog 1 input terminals. This will create a +2VDC to +10VDC voltage at

the terminals and generate a fault if the voltage drops below 1.5VDC (3 mA).

Second, the user would set the Analog Input Offset to generate a –6VDC offset (program item

850= -6.0). This creates a –4VDC to +4VDC voltage from the original +2VDC to +10VDC voltage.

Next, the user would set the gain to 2.5 (program item 852=2.5). This creates a –10VDC to

+10VDC voltage from the offset voltage of –4VDC to +4VDC.

Finally, the user would set the input polarity to normal (program item 852=0), so the input is not

inverted. See Figure 14.

Example 2: A user wants a 0V to 5VDC signal at Analog Input 2 to control a unidirectional pump

(command range of 0 to +10VDC).

First the user would disable the current fault for Analog Input 2 (program item 863=0).

Second, the user would configure the input for 0VDC voltage offset (program item 860=0) since the

input voltage needs no offset for this particular example.

Next, the user would set the gain to 2 (program item 861=2) to create a 0 to +10VDC voltage from

the offset voltage of 0 to +5VDC.

Finally, the user would set the input polarity to normal (program item 862=0), so the input is not

inverted. See Figure 14.

Figure 14: Analog Inputs Example




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4.4.2 LVDT Fine-Adjustable Analog Input Configuration


840 0 to 63 LVDT: Course Gain

841 0 to 63 LVDT: Fine Gain

843 0 to 1023 LVDT: Offset

845 0 to 1 LVDT: Polarity

Table 14: LVDT Input Configuration

Program items 840 through 845 are used to configure the LVDT. The LVDT Input is configured

from the Analog IO Configuration Form (select menu Diagnostics and then Configuration). See

Figure 15.

The adjust program item allows the module to be placed in Pump Controller Adjust Mode. This

is a special operating mode designed for adjustment of the LVDT inputs. Please refer to Section

4.4.5 for a thorough discussion of this adjustment mode.

Course and Fine Gains: Since greater resolution is needed to scale and offset the input of the

sinusoidal LVDT input signals, the gain and offset are not done directly in the microcontroller, but

performed through electrical circuitry. The Course and Fine Gain increases over the range from 0 to

63. The LVDT should be configured using the algorithm discussed in Section 4.6.1.

Offset: The LVDT offset, like the course and fine gains, manipulates hardware circuitry. An

offset setting ranges from 0 to 1023 to offset the LVDT from -10V to 10V. A 512 setting has a

0V offset. Please refer to Section 4.6.1 for a discussion of the LVDT Adjustment Algorithm.

Polarity: The Polarity setting is set to either (0) Normal or (1) Inverted. Inverting the input in this way

would be equivalent to reversing wire leads to the module. In fact, a better long term solution to using

the invert setting would be to reverse the wire leads to the module.

Figure 15: LVDT Input




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4.4.3 Programmable Analog Outputs

There are 2 programmable analog outputs (see Figure 16). Analog Output 1 (program item 930) is

located on the front of the EPC typically used as a test point for debugging. Analog Output 2

(program item 933) is located on terminals 7 and 8 typically connected to an analog input of a

PLC.

Figure 16: Analog Outputs

The test point can easily be monitored externally. The signals for the programmable outputs are

selected in the Analog IO Configuration Form. Available Diagnostic signals are shown in Table

15.

Selection Diagnostic

0 Output Disabled

1 Analog Input 1

2 Analog Input 2

3 Analog Input 3

4 Analog Input 4 (LVDT)

5 Current Feedback Signal

6 LVDT sine wave excitation signal

7 +12VDC Supply

8 -12VDC Supply

9 Servo Driver Output

10 Command to Pump Controller (Output of Active Function Program)

11 Ramp Table 15: Diagnostic Signals




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4.4.4 Servo Valve Driver with Stroke Feedback

The Servo Valve Driver Configuration allows for selecting the pump adjust mode, monitoring the

driver current and stroke feedback, and scaling and offsetting the driver. The scaling and offsetting

parameters are only available for EPC modules running firmware Version 1.10 or later. The Servo

Driver information is located in the lower left corner of the Analog IO Configuration Form (see

Figure 17).

Figure: 17: Servo Valve Driver

4.4.4.1 Servo Attenuation and Offset

The Servo Driver configuration settings are used together with the Output Polarity and

Output Current Limit from the Pump Controller Configuration Form to configure the servo

driver output. The Configuration Settings are applied AFTER the Polarity setting and

BEFORE the Current Limit Setting.

The Servo Driver Attenuation parameter (menu item 965) attenuates the servo driver signal.

Valid entries are from 0.4% to 100% at approximately 0.4% increments. The Attenuation

Setting is applied immediately AFTER the Polarity setting and BEFORE the Servo Driver Offset

Setting.

The Servo Driver Offset parameter (menu item 966) applies an offset voltage to the servo

driver signal. Valid entries are from -10.0VDC to +10.0VDC at 0.1VDC increments. The

Offset Setting is applied immediately AFTER the Attenuation setting and BEFORE the

Current Limit Setting.

The Servo Valve Driver current is shown in voltage units. The driver range of -10V to 10V is a

scaled value of the output current. Depending on the EPC part number, the output current may

be different for the same output voltage. See the table 16 for more information.

EPC P/N Driver Current Current Current Current Current

L723888- Current @ -10V @ -5V @ 0V @ 5V @ 10V

310 +/-800mA -800mA -400mA 0mA 400mA 800mA

311 +/-800mA -800mA -400mA 0mA 400mA 800mA

312 +700mA 0mA 0mA 0mA 300mA 700mA

314 +/-250mA -250mA -125mA 0mA 125mA 250mA Table 16: Driver Output




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4.4.4.2 Stroke Feedback Device

The Stroke Feedback Device information is displayed in both a bar graph and numerical form.

The Feedback Device is determined by menu item 800 located in the Pump Controller Form.

Typically for pumps, Analog Input 4 (LVDT) is selected.

4.4.4.3 Adjustment Mode

The Pump Controller Adjust Mode is a special operation mode in which an Adjust Mode Toggle

Command controls the servo driver rather than the Pump Controller or Active Function block.

The Adjust Mode works optimally with Main Pumps off and Pilot Pumps pressurized. Adjust

mode is set by pressing the Adjust mode Command button from the Analog IO Configuration

Form. Adjust mode is indicated by a System Message.

The Adjust Mode Toggle Command will alternately command neutral, full positive and full

negative current to the driver. Initially, the output toggle is at the neutral (zero) current

position.

The Adjustment toggle command is monitored from the PC interface. The Analog I/O

Configuration Form has a toggle command button. The display and bar graph indicator will

show the value of the toggle.




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The Adjust Mode Command Toggle is a special function available in Adjustment mode that

will alternately command neutral, full positive and full negative current to the driver. If in

Adjustment mode, the following graphics are shown.

The graphic will appear as in Figure 18 when the toggle sets the servo valve driver at neutral

current (valve approximately centered at 0ma):

Figure 18: Neutral Current

The graphic will appear as in Figure 19 when the toggle sets the servo valve driver at

maximum positive current:

Figure 19: Positive Current

Finally, graphic will appear as in Figure 20 when the toggle sets the servo valve driver at

maximum negative current:

Figure 20: Negative Current




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4.4.5 LVDT Adjustment Algorithm

Both the HP Limiter and Stroke Controller portions of the Pump Controller module rely on the LVDT

being configured correctly. Typically, there are three (4) configuration parameters for each LVDT

(Refer to Section 4.4.2 for a complete overview):

Polarity

Offset

Course Gain

Fine Gain

The general sequence of operations for LVDT scaling is to

Set LVDT polarity to normal.

Place the EPC in Adjust mode.

Alternately Adjust the LVDT Offset and Gains until configured.

Return EPC to normal operation mode.

4.4.5.1. Determining LVDT Configuration Range

The LVDT input should be scaled to match the range of stroke command. The range of

stroke command is a factor of whether the pump is designed for uni- or bi-directional flow.

Servo valves are commanded with current: a positive current command will move the valve in one

direction while a negative current command will move the valve in the opposite direction. A neutral

(zero) current command will remove command to the valve: the valve might stay in its current

state, or it may move in either direction.

For a uni-directional pump, only one port is available and the stroke can supply 0 to 100% of

the rated flow. The LVDT should be configured so that the maximum positive toggle command

will produce the equivalent of a +10VDC command for the LVDT input. The maximum

negative toggle command should produce the equivalent of a 0 VDC command at the LVDT

input. The range of 0 to +10VDC corresponds to DAC values of 2048 to 4095, or a percentage

of 0 to +100% (refer to Section 5.1 for a discussion of the Diagnostic Representation of

Numbers).

For a uni-directional pump, the midpoint command is +5VDC (DAC value of 3072 or +50%

stroke).

For a bi-directional pump, two ports are available and the stroke can supply 0 to 100% of rated

flow in each direction. Like the uni-directional valve, the LVDT should be configured so that the

maximum positive toggle command will produce the equivalent of a +10VDC command for the

LVDT input. The maximum negative toggle command, however, should produce the equivalent

of a -10VDC command for the LVDT input. The range of -10VDC to

+10VDC corresponds to DAC values of 0 to 4095, or a percentage of -100% to +100% (refer to

Section 5.1 for a discussion of the Diagnostic Representation of Numbers).

For a bi-directional pump, the midpoint command is 0VDC (DAC value of 2048 or 0%

stroke).




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4.4.5.2 Adjustment Algorithm

The following algorithm may be used to optimally configure the unit. The PC Interface

includes a Microsoft Excel ™ template (EPCConfig.xlt) that can be used to optimize the

setup. The Excel template is also available through e-mail by request to

[email protected].

1. Place the module in Adjustment mode (refer to Section 4.6.1.1).

2. Use an Initial setting of Offset = 512, Course Gain = 0, and Fine Gain = 0.

3. Toggle the Pump Command and note the LVDT readings at the maximum positive and

negative toggle commands (refer to Section 4.4.4.3 regarding toggle command).

4. Determine the midpoint of these two LVDT readings and compare with the desired

midpoint reading (see previous Section).

5. Adjust the LVDT offset so that the two LVDT readings have the desired midpoint

reading.

6. Adjust the LVDT course gain upwards from the initial setting such that the positive

and negative toggle commands produce LVDT signals as large as possible without

either toggle command producing an LVDT signal out of the LVDT configuration

range..

7. Repeat steps 3 through 6 until a one-digit course gain change is unable to produce

LVDT signals within the configuration range. For a uni-directional pump, a positive

toggle command should produce an LVDT signal slightly less than +10VDC and a

negative toggle command should produce an LVDT signal slightly greater than

0VDC. For a bi-directional pump, a positive toggle command should produce an

LVDT signal slightly less than +10VDC and a negative toggle command should

produce an LVDT signal slightly greater than -10VDC.

8. Once the Course gain is found, adjust the fine gain upward from the initial setup. Do

not adjust the course gain and fine gain concurrently since the two do not

function together in a straightforward linear fashion.

9. Determine the midpoint of these two LVDT readings and compare with the desired

midpoint reading (see previous Section).

10. Adjust the LVDT offset so that the two LVDT readings have the desired midpoint

reading.

11. Adjust the LVDT fine gain downward from the initial setting until one of the two pump

toggle commands is just under the pump range.

12. Repeat steps 9 through 11 until a one digit fine gain change produces LVDT signals

spanning the entire configuration range. For a uni-directional pump, a positive toggle

command should produce an LVDT signal of +10VDC and a negative toggle command

should produce an LVDT signal of 0VDC. For a bi-directional pump, a positive toggle

command should produce an LVDT signal of +10VDC and a negative toggle command

should produce an LVDT signal of -10VDC.


mailto:[email protected].



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Example 1: Balance an LVDT for a bi-directional pump (The example can be followed from

the Example 1 sheet of the Excel template.)

Toggling with the initial values produces a low reading of -92.50% and a high reading of -

40.60%. These readings should be offset to produce a low reading of -25.95% and a high

reading of +25.95%. This is calculated by finding the midpoint of the current readings (-90.50

+ -40.60)/2 = -66.55 and comparing that to the desired midpoint (a bi-directional pump should

have a midpoint at 0). Adding 65.55 to each value results in -90.50 + 65.55 = -25.92 and -

40.60 + 66.55 = 25.95. This setting is reached when the Balance is set to 411 (low and high

readings of 25.90 and 26.20, respectively). Notice that at this point approximate values are

good enough.

The user then attempts to adjust the gain to near saturation. At a Course gain = 30 the low

reading is -91.60% while the high reading is -9.20%. The next gain (31) actually saturates the

low reading to -100%, so 30 is used.

The user then attempts to offset the readings to low=-41.20% and high=+41.20%. The user

finds this at Offset=334.

In a similar fashion, the user continues alternately selecting offset and course gain values. At

step 6, a change in course gain saturates the low reading, so the user has successfully found the

optimal setting for course gain. The user continues as before, but this time uses the fine gain to

set the near saturation gains.

At step seven the user finds that a fine gain change from 5 to 6 saturates both readings.

LVDT configuration is complete.

Example 2: Balance an LVDT for a unit-directional pump. The only difference between this

and the previous example would be that the midpoint would be +50% rather than 0%. The user

is invited to view the Example 2 sheet of the Excel template for this example.




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4.5 Advanced Configuration The Advanced Diagnostics Form contains the setups for Horsepower Limiting and Ramping functions.

4.5.1 Horsepower Limit Factor Calculation

The horsepower limit factor can be used to limit the power consumed by the hydraulic pump. To

limit horsepower, the user first enters a value for the HP factor: this factor produces a PQ

(pressure-flow) curve that defines a certain horsepower region (Figure 21). The user then sets the

Pump Controller module with the proper settings for stroke and pressure feedback (see Section

4.3.2.3).

The horsepower limit factor can be determined in two ways: experimentally or theoretically.

Figure 21: PQ (HP) Limit Curve

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4.5.1.1 Experimental HP Limit Factor

For the Experimental HP Limit Factor, the user builds up pressure and increases stroke until the

motor supplies the maximum rated current. This procedure requires a program that allows for

direct stroke command, so a good function program to use would be the Simple Flow Program

(refer to Section 4.2.6).

To determine the HP Limit Factor, the user must first configure the EPC for stroke feedback

(Section 4.4.2) and connect a pressure transducer to an available analog input. An additional

analog input can be used for stroke command.

The user then sets the HP factor to an initial setting of 100% and rigs the hydraulic circuit to

build maximum pressure. Once this achieved, the user uses a current transducer and multimeter

to measure motor current. Stroke to the pump is slowly increased, and the multimeter is

monitored until the current to the motor is at the maximum rated current. At this point, the user

notes the DAC reading for pressure and stroke.

The HP factor is determined by the formula

𝐻𝑃𝑓𝑎𝑐𝑡𝑜𝑟 = (𝑄𝐷𝐴𝐶 − 20480)(𝑃𝐷𝐴𝐶 − 2048)

(2048)(2046) × 100%

The PC interface allows a one-touch solution from the Advanced Configuration Form. The

user simply presses the HP Experiment push-button once the maximum current is reached.




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4.5.1.2 Theoretical HP Limit Factor

The HP limit factor can also be determined by the theoretical formulas. For metric units the

horsepower factor is determined by the equation:

𝐻𝑃𝑓𝑎𝑐𝑡𝑜𝑟 = 6.0 × 107 × 𝑃𝑜𝑤𝑒𝑟

𝐷𝑀𝐴𝑋𝑃𝑋𝐷𝐶𝑅𝑁×

Where

Power is the motor rating in kW

DMAX is the maximum displacement of the Pump in ml/rev

PXDCR is the maximum measured pressure in Bars

(i.e., the pressure corresponding to a 10VDC or 20mA reading)

N is the speed in rpm

is the pump efficiency

The user may also use conventional English units:



Where

Power is the motor rating in horsepower

DMAX is the maximum displacement of the Pump in in3/rev

PXDCR is the maximum measured pressure in PSI

(i.e., the pressure corresponding to a 10VDC or 20mA reading)

N is the speed in rpm

is the pump efficiency

48




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Example 1: What HP factor would be used for a PVG075 powered by a 25 HP motor

rotating at 1500 rpm. The EPC uses a 5000 PSI pressure transducer to measure pressure.

From Oilgear Bulletin 47019, a PVG075 has a maximum displacement of 4.60 in3/rev and an

overall efficiency of 80% at maximum pressure. These values are used in the formula:



= 4.0 × 107 × 25

(4.60)(5000)(1500)× 0.80

= 23

Example 2: What HP factor would be used for a PVG100 powered by a 50 kW motor

rotating at 1500 rpm. The EPC uses a 400 Bar pressure transducer to measure pressure.

From Oilgear Bulletin 47019, a PVG100 has a maximum displacement of 98.3 ml/rev and an

overall efficiency of 85% at maximum pressure. These values are used in the formula:



= 6.0 × 107 × 50

(98.3)(400)(1500)× 0.85

43

From the Advanced Configuration form, the user enters each of the variables in the desired

system of units. Once this is done, the use presses the HP Theory command button to create a

new value for the HP factor.

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4.5.2 Ramp Configuration

The EPC module provides one ramp module and is configured by program items 870 through 874. The

ramp can be configured from the Advanced Configuration Form (select Diagnostics and then

Advanced).


870 0 to 4 Ramp 1: Source

871 1 to 255 Ramp 1: Acceleration Rate

872 1 to 255 Ramp 1: Acceleration Step

873 1 to 255 Ramp 1: Deceleration Rate

874 1 to 255 Ramp 1: Deceleration Step

Table 17: Ramp Configuration

Source: The Source selects the Analog Input used as the ramp input. Valid entries are (0) No

Ramp, (1) Analog Input 1, (2) Analog Input 2, (3) Analog Input 3, or (4) LVDT (Analog Input 4). If

No Ramp is selected, the ramp module will be disabled and the ramp function will be equal to

2048 DAC counts.

Rate and Step: The Ramp module provides different ramping rates for acceleration and

deceleration. Acceleration is defined as increasing stroke, while Deceleration is defined as

decreasing stroke. Ramping from +5V to +10V is acceleration, while ramping from +10V to +5V is

deceleration. Ramping from -5V to -10V is also acceleration, since -10V provides greater stroke

than -5V. Conversely, ramping from -10V to -5V is deceleration.

Since the EPC is a digital controller, the ramp is actually a staircase-like signal. The Rate describes

the time length of each step and is expressed in whole number multiples of the closed loop update

rate. The Step describes the potential step at each interval and is expressed as DAC counts.

The closed loop response is 1600 Hz. The Ramp Rate can be expressed in Volts/second with the

equation

𝑅𝑎𝑚𝑝 𝑅𝑎𝑡𝑒 (𝑉𝑜𝑙𝑡𝑠

𝑠) = [𝐶𝑙𝑜𝑠𝑒𝑑 𝐿𝑜𝑜𝑝 𝑅𝑒𝑠𝑝𝑜𝑛𝑠𝑒] × 0.004884 ×

𝑆𝑡𝑒𝑝

𝑅𝑎𝑡𝑒

The larger the ramp rate or step is, the more course the ramp stair casing will be. The time length of

each step can be computed from the Rate setting:

Time Length (seconds) 𝑅𝑎𝑡𝑒

[𝐶𝑙𝑜𝑠𝑒𝑑 𝐿𝑜𝑜𝑝 𝑅𝑒𝑠𝑝𝑜𝑛𝑠𝑒]

Potential Step (Volts) Step 0.004884

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The Potential Step can be computed from the Step setting:

Example 1: A Rate of 255 and a Step of 1 is used for a 1600 Hz module. The Ramp Rate in

Volts/second is

Ramp Rate = 1600 x 0.004884 x (1 / 255) = 0.03064 Volts/second

so a 10 Volt step would ramp over a period of 326 seconds (5 minutes:26 seconds).

The setting of Rate = 255 and Step = 1 results in the slowest ramping rate.

Example 2: A Rate of 1 and a Step of 255 is used for a 1600 Hz module. The Ramp Rate in

Volts/second is

Ramp Rate = 1600 x 0.004884 x (255 / 1) = 1993 Volts/second so

a 10 Volt step would ramp in only 5 milliseconds.

The setting of Rate = 1 and Step = 255 results in the quickest ramping rate.

A user should select a ramp rate that is close to a desired value, while not producing an

undesirable step. Generally, the lower the values for rate and step, the smaller the step.

Example 3: Which of the following are the optimal settings for a 0.5 Volt/second ramp?

(a) Rate = 15, Step = 1

(b) Rate = 31, Step = 2

(c) Rate = 47, Step = 3

(d) Rate = 125, Step = 8

Assuming a 1600 Hz closed loop response, the settings for (a) result in:

Ramp Rate = 1600 x 0.004884 x (1 / 15) = 0.5210 Volts/second or

a 1 x 0.004884 = 5mV step every 15/1600 = 9 milliseconds.

Similarly, the settings for (b), (c), and (d) result in

(b) Ramp Rate = 0.5042 Volts/second (10mV step every 19 milliseconds)

(c) Ramp Rate = 0.4988 Volts/second (15mV step every 29 milliseconds)

(d) Ramp Rate = 0.5001 Volts/second (39mV step every 78 milliseconds)

The optimal setting depends on the ramp requirements and system dynamics. If time is not critical,

the settings for (a) which have the smallest step size would be optimal. If time is critical and the

system dynamics allow for a larger step size, the settings in (d) should be used since the ramping is

closer to the desired value (0.5001 V/s rather than 0.5210 V/s).

Deductive reasoning can be used to find the rate and step values for a desired ramp.




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Example 4: What settings would be used to produce a 5-second ramp for a 0 to 10 Volt step

command?

A 10 Volt / 5 second = 2 Volt/second ramp is desired. Since both the Rate and Step have values from

1 to 255, an arbitrary value of 10 is chosen for the Step and the Rate value is calculated:

Ramp Rate = [ Closed Loop Response ] 0.004884 Step / Rate

Rate = [ Closed Loop Response ] 0.004884 Step / [Ramp Rate]

= 1600 0.004884 ( 10 / 2 ) = 39

A step of 10 and rate of 39 make a 2.0037 Volt/second ramp (48 mV step every 24 milliseconds).

Because 10/39 is approximately 1/4, we would expect a step of 1 and a rate of 4 to be close to the ramp

rate, yet provide a smaller staircase. Accordingly, a step of 1 and a rate of 4 create a 1.95 Volt/second

ramp, this time with a 5 mV step every 0.6 milliseconds.

PC Interface: The PC interface contains a worksheet for ramp values (Advanced Diagnostics Form).

The user selects a desired ramp rate and one of five resolution factors. The worksheet calculation

function will display the results of the most optimal settings.




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5 Module Diagnostics

The EPC has diagnostics available through both the front of the EPC (LEDs and testpoint) and the PC

interface. However, due to the extensive features of the controller, the PC interface is the recommended

diagnostic tool.

5.1 Diagnostic Representation of Numbers

Throughout this manual, reference has been made to DAC counts, percentages, and voltages. DAC

count representation is the basis for all other diagnostic representation, since all internal numbers are

represented within the controller as DAC (Digital-to-Analog Converter) counts.

5.1.1 DAC Counts

Most Diagnostic numbers are stored as a 12-Bit number from 0 to 4095. For an input or output

variable, 0 DAC counts is equivalent to -10VDC while 4095 DAC counts is equivalent to +10VDC.

2048 DAC counts represents the midpoint of -10VDC and +10VDC, or 0VDC.

5.1.2 Voltage and Percentages

The PC interface allows a great range of diagnostic options. For most diagnostic Forms, the user can

select to view input and output values as voltages or percentages. This feature is particularly helpful

in LVDT adjustment.

A comparison summary of the different number representation follows:

Volts: -10V -5V 0V +5V +10V

Percentage: -100% -50% 0% +50% +100%

DAC (decimal): 0000 1024 2048 3072 4095

5.2 Basic Diagnostics on Front Panel

On the front of the EPC are 3 bi-color LEDS. These indicate Run / Fault conditions,

Valve Current and Feedback. In addition, there is a testpoint labelled Analog Output 1.

See Figure 22 for the location of the LEDS and Testpoint.

Figure 22




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5.2.1 Run / Fault LED

The bi-color LED provides diagnostics information about the Run / Fault conditions. The Run

/ Fault LED has several modes. See Table 22 for detail information on high priority faults and

Table 23 for system messages.

Mode Description

Steady Green EPC has power (24V supply).

Flashing Green EPC is communicating with a PC.

Steady Red High priority faults.

Flashing Red System messages and during power on for approximately 2 seconds.

Table 18: Run / Fault LED

5.2.2 Valve Current LED

The bi-color LED provides diagnostic information about the Valve Current. The color of

Valve Current LED indicates the direction of the current to the valve. The intensity of the

Valve Current LED indicates the amount of current to the valve.

Color Direction Intensity Current

Green Positive Low Low Green

Positive High High Amber

Negative Low Low Amber

Negative High High

Table 19: Valve Current LED

5.2.3 Feedback LED

The bi-color LED provides diagnostic information about the Feedback. The color of the Feedback

LED indicates the direction of the Feedback. The intensity of the Feedback LED indicates the amount

of Feedback.

Color Direction Intensity Feedback

Green Positive Low Low Green

Positive High High Amber

Negative Low Low Amber

Negative High High

Table 20: Feedback LED

5.2.4 Test Points

Two test points are accessible from the front of the EPC. The first is directly below the USB port,

which is a copy of the signal driving analog output #2. The second, which is toward the bottom,

is a copy of the signal that drives analog output #1. They accept 0.080” test probes.

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5.3 Basic Diagnostics with PC Interface

The Basic Diagnostics are easily identifiable through the Analog IO Configuration Form. Items

include Digital Input, Digital Output, Analog Input 1, Analog Input 2, Analog Input 3, LVDT (Analog

Input 4), Programmable Outputs and Servo Driver Output. See Figure 23 for details. In addition,

diagnostic values are available throughout as needed.

Figure: 23: Analog IO Configuration Form




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5.4 Programmable Outputs Diagnostic

There are 2 programmable outputs. Analog Output 1 (program item 930) is located on the front of the

EPC typically used as a test point for debugging. Analog Output 2 (program item 933) is located on

terminals J3-1 and J3-3 typically connected to an analog input of a PLC.

The test point can easily be monitored externally. The signals for the programmable outputs are

selected in the Analog IO Configuration Form. Available Diagnostic signals are shown in Table 21.

Selection Diagnostic

0 Output Disabled

1 Analog Input 1

2 Analog Input 2

3 Analog Input 3

4 Analog Input 4 (LVDT)

5 Current Feedback Signal

6 LVDT sine wave excitation signal

7 +12VDC Supply

8 -12VDC Supply

9 Servo Driver Output

10 Command to Pump Controller (Output of Active Function Program)

11 Ramp Table 21: Diagnostic Signals

5.5 Advanced Diagnostics

Advanced Diagnostics are viewable in the upper right hand corner of all Forms listed as High

Priority Faults and System Messages. See Figure 23.

5.5.1 Module Faults

Module Faults are high priority faults that show EPC failure.

There are up to 8 (eight) module faults. Any fault will cause the PC interface to register a module

fault. The eight faults are represented by a fault bit number from 0 to 7. A fault condition will be

represented by the high priority box turning red. In addition, a triangle with an exclamation sign inside

it indicates the specific fault.




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Fault Bit Fault Condition

0 Spare Fault Condition




4 LVDT Excitation Signal Fault

5 -12VDC Supply Fault

6 +12VDC Supply Fault

7 Non-Volatile Memory (EEPROM) Fault

Table 22: Fault Condition Codes

5.5.2 System Messages

System Messages display system messages about the EPC.

There are up to 8 (eight) module system messages. Any message will cause the PC interface to

register a module system message. The eight faults are represented by a fault bit number from 0 to

7. A fault condition will be represented by the system message box turning red. In addition, a

triangle with an exclamation sign inside it indicates the specific fault.

Fault Bit Fault Condition

0 Line Break Warning - Analog Input 1


2 Digital Output Error


4 Spare Run-Time Message

5 Driver Current Fault

6 Module Closed Loop Warning

7 Module LVDT Adjustment Mode

Table 23: System Messages

Generally, a module message does not describe a module failure, but communicates that the EPC

is probably configured incorrectly or a temporary fault condition exists.

For instance, the module can be configured to display a system message when the General

Purpose Analog Input is less than 3mA (refer to Section 4.4.1). This condition would result in a

run-time fault being generated. The most probably cause of the Digital Output Error is to

incorrectly connect the output as a digital input.




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6 Technical Data

6.1 Module Pinout

Output 2

back

Oscillator

Figure 24: Module Pinout

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6.3 Specifications

Supply Voltage: +24VDC (18VDC to 36VDC) Supply

Current (Run): 100mA + Maximum Driver Current

Supply Current (Start-Up): 1200mA

Maximum Driver Output: +/- 1000 mA (PWM) Closed Loop Update Rate: 1600 Hz

Size: 23mm wide 91mm height 88mm length

0.87in. wide 3.56in. height 3.44in. length

(4.53in. length with connector)

Ambient Temperature: 0 °C to +70 °C

Mounting: DIN EN 50022-35

6.4 IO Summary

Digital Input: 1 Digital High = 5VDC to 36VDC Digital

Output: 1 Vsupply (short circuit protected) Analog

Inputs (General Purpose): 3 Voltage (Potential) mode: +/- 10VDC

Current mode: 0 to 20mA or 4 to 20mA (see Note 3)

LVDT Inputs: 1 approximately 0 to 20VDC

Test Point Output 1 +/- 10VDC (see Note 1)

Programmable Outputs 2 +/- 10VDC (see Notes 1, 2)

Notes:

1. Output signal programmable (refer to Section 5.3)

2. Includes testpoint.

3. A 500 resister is required across the analog input to convert the current into voltage. See Figure

20 for a typical connection for current mode on Analog Input 2.

6.5 Cable Recommendations and Terminal Information

Cable recommendations and terminal information are as follows (equivalent cable may be substituted).

EPC Connection Cable Type Gauge Belden P/N Length (max)

Linear Torque Motor 2 Conductor Shielded #22 AWG 8761 250 Feet Linear

LVDT 4 Conductor Shielded #24 AWG 9729 250 Feet

PWM Valve 2 Conductor Shielded #18 AWG 8760 250 Feet

PWM LVDT 4 Conductor Shielded #24 AWG 9729 250 Feet

Table 24: Cable Recommendations

Terminal Number Hole Diameter Gauge

All Terminals 1.1 mm 16 - 26 AWG

Table 25: Terminal Information

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7 Technical Support

For US customer support, contact The Oilgear Company

The Oilgear Company

2300 So. 51st. Street

PO Box 343924

Milwaukee, WI USA 53234-3924 (Shipping

Address Zip Code is 53219-2340)

Voice Support: 414-327-1700

Fax Support: 414-327-0532

E-Mail Support: [email protected]

Website: www.oilgear.com

For European Technical Support, contact the Electronics Division of Oilgear GmbH:

Oilgear

Im Gotthelf 8

D-65795 Hattersheim

(Industriegebiet Eddersheim)

Germany

Voice Support: (+49) 6145 377 0

Fax Support: (+49) 6145 30770

E-Mail Support: [email protected]


mailto:[email protected]


mailto:[email protected]



ELECTRONIC



8 Ordering Information

EPC Modules are available in three standard options: Non-Configured Modules, Standard

Configured Modules, and Small Engineered System Units.

Non-Configured Modules are intended for customer-engineered systems and OEM applications. It is

expected that the user has completed Oilgear training or has significant experience with hydraulic systems

and Oilgear electronics. Wiring diagrams and installation drawings are not provided beyond the standard

bulletin and/or PC Interface Software online help (both items ordered separately). All accessory items

should be ordered as separate line items (please see the Accessories Section for more information).

Standard Configured Modules are intended for standard single-unit applications or replacement parts for

Small Engineered Systems. The modules are pre-programmed by Oilgear prior to shipping, but may

require some field adjustment. Wiring diagrams and installation drawings are not provided beyond the

standard bulletin and/or PC Interface Software online help (both items ordered separately). All accessory

items should be ordered as separate line items (please see the Accessories Section for more information).

Small Engineered System Units are fully engineered and tested application system components

including customized wiring diagrams and installation drawings. The number of EPC modules

determines the base price of the Small Engineered System. In addition to wiring and installation

drawings, Oilgear provides Configured Modules to simplify replacement parts. All accessory items

should be ordered as separate line items (please see the Accessories Section for more information).

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Documents

EPC - Oilgear SERVO AMPLIFIER MODULE Part Number L723888-3xx ELECTRONIC Telephone: (414) 327-1700 Oilgear Street Issued: April 28, 2015. EPC SERVO AMPLIFIER MODULE